I walked from Soi 77 to the white 'lookout tower' which is about 10 minutes from Takiab, then walked back and counted on the way back as I noticed so many on the walk South. That was about 11 am as I was a bit late today.

Edit : Will you see them in the dark ?

Also a few were ringed with purple round the edge and looked beautiful for a nasty stingy thing.

Just back, and it was just past high tide. I go on the beach at Soi 75 and walk to Marakesh and back (oldest dog is restricted to how far she is allowed to walk). A lot of the beach is floodlit at night, so no problem seeing them (we also take torches), although we had to look hard to see the blue, but yes, most were blue, and there were loads of the beasties, made worse by our rottweiler who thinks a good game is to fetch them from the sea and plonk them on the beach like pancakes - there are loads out there, but I don't think the sting can be too bad on these. Our dog barely flinched at the venom, whereas some cause her to really shake her head.

I agree, some are really beautiful - a shame that they can cause so much discomfort.